create indudival particles with particle tool...apply some wind, gravity and drag fields so tht u get the req movement..then instance the particle with the modeled mesh...or a simple plane with texture will do.....make a couple of diff leaves to get the randomness if reqd..
hope this helps

In that case you can create particles as individual by using of particle tool and apply some wind, gravity and drag the fields as your requirements. For this process you have required enough memory space otherwise you get the error.

This script prepares a scene for a realistic simulation of falling tree-leaves. You can also make them blow in the wind, or collide with the ground or other objects, etc.
The simulation itself is done with nCloth. The idea is to have one or several leaf models, and their corresponding low-res models (sub-divided and shaped planes, basically). This script will:
1) Scatter as many copies as you want of those leaves, on the NURBS surface of your choice (with random rotations), avoiding intersections.
2) Combine all the low-res models into a single object (named "simLeaves_Lo") , which will be simulated with nCloth.
3) Apply wrap deformers to the high-res leaves, so they will have the movement and deformations of the simulated low-res leaves.
4) Set basic parameters of the nCloth simulation, although you will have to tweak those depending on the scale of your scene/leaves and desired behaviour.

In former times the leaves of the trees of the fall, immediately begin to be boiled out. What they begin to have left the without delay. During these proceedings in the land of food which sustains a good, hinder rays of the sun from thence, he can kill the grass labor. First a grass to death by removing it be said as ideal. Leaves steeped in the fall of the fall of the pose-and-dice of guests the front walk.